1. Field of the Invention
The present invention relates to a film cooling structure in which jetting holes are formed on a wall surface, which faces a passage of high-temperature gas, of such as moving blades, static blades, and an inner cylinder of a combustor of a gas turbine. A cooling medium jetted from the jetting holes flows along the wall surface so that the wall surface is cooled by the cooling medium.
2. Description of the Related Art
Conventionally, on the wall surface of such as the moving blade of the gas turbine, many jetting holes pointing in the same direction are formed. By a film flow of a cooling medium like air jetted from these jetting holes, the wall surface aforementioned exposing to high-temperature gas is cooled. JP-A 4-124405 shows in FIG. 3 thereof this kind of configuration.
However, conventionally, the cooling medium jetted from the jetting holes into the passage of high-temperature gas is easily separated from the wall surface, so that the film efficiency indicating the cooling efficiency on the wall surface is low. Generally, the film efficiency is about 0.2 to 0.4. Here, the film efficiency is ηf,ad=(Tg−Tf)/(Tg−Tc), where Tg indicates a gas temperature, Tf a surface temperature of the wall surface, and Tc a temperature of the cooling medium on the wall surface.